80 



THE CERATOPSIA. 



ward interiorly. The head is restricted to the median half of the proximal end of the humerus 

 and it is produced forward. The shaft of the humerus is very broad proximally, with the 

 transverse diameter several times greater than the fore and aft. Below 

 the deltoid ridge the transverse diameter of the shaft is more restricted 

 and the antero-posterior somewhat increased, so that the bone becomes 

 elliptical in cross section, with the transverse diameter still the greater. 



Most of the more important characters of the humerus are shown in 

 fig. 85. 



I do not find in the collections from the Judith River beds either a 

 femur or tibia agreeing with the measurements given by Cope for those 

 bones in Ms original description of the genus and species. There are 

 two femora, both of which are much too long. There are also two 

 complete tibiae in the collection, and the smaller of these, though longer 

 and with the proximal end broader than given by Cope, may perhaps be 

 the one referred to in his original description. It is much crushed and 

 distorted, but was evidently comparatively strong and heavy, and in 

 this respect it seems somewhat out of proportion with either of the 

 femora mentioned above. The astragalus is still in position at the distal 

 extremity, as shown in fig. 87. 



A fibula in the collection is of the same length as that given for the 

 tibia, and may perhaps pertain to the same skeleton as the type, although 

 there is no other evidence as to this association. It is much compressed 

 throughout its entire length, but is antero-posteriorly expanded at the 

 extremities and more especially at the proximal extremity, as shown in 

 fig. 88. 



Fig. 88. — A, Anterior view of 

 fibula of Mono clonius 

 crassus Cope, No. 3998, 

 AmericanMuseum of Nat- 

 ural History; B internal 

 view of same, a, Prox- 

 imal end; o, distal end. 

 One-eighth natural size. 



Principal measurements of Monoclonius crassus. 



The parietals: • Mm - 



Estimated length of parietals (type 3998) along median line 500 



Greatest expanse of parietals .' - 716 



Depth of median posterior emargination 64 



Antero-posterior diameter of parietal foramen - 310 



Transverse diameter of parietal foramen 205 



The frontal, No. 3997: 



Greatest length of frontal : 301 



Height of horn above superior border of orbit 75 



Antero-posterior diameter of orbit - - - - - 91 



Width of skull between orbits as determined by doubling distance from orbital border to frontal suture. 254 



Three [four] anterior cervicals, No. 3998: 



Combined length of three [four] coossified centra 234 



Transverse diameter of cup for condyle 72 



Vertical diameter of cup for condyle - - 77 



Depth of cup for condyle - — 28 



Length of sacrum (3998a) - - - - 746 



Expanse of diapophyses of fifth and sixth sacrals - 303 



Estimated length of ilium (3998) - 850 



Depth of same just back of ischiac peduncle 177 



Combined length of scapula and coracoid (3998a) - 820 



Length of scapula alone - - 660 



Length of coraco-scapular suture - 183 



Greatest diameter of coracoid foramen in same 31 



Greatest length of humerus (399S) 560 



Transverse diameter at proximal end as restored -- 205 



Transverse diameter at point of greatest constriction - 85 



Greatest length of shorter of two femora mentioned in text (3998?). 625 



Greatest length of shorter of two tibiae mentioned in text (3998?) - 53S 



Greatest, length of fibula mentioned in text (3998?) - 505 



